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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 4 (1997), S. 4382-4387 
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Large-scale coherent motions of a current sheet such as flapping or tearing of the entire current sheet are studied. The basic magnetohydrodynamic (MHD) equations are integrated over the thickness of the current sheet, and linear analysis is applied to obtain the modified dispersion relations for the MHD fast, Alfvén, and the slow waves under non-zero background cross-sheet current. The dispersion relation for the fast and slow modes contains an imaginary part, because energy is exchanged between the wave and the background sheet current. A short-wavelength MHD slow wave propagating against/along the magnetic tension force is unstable/stable, whereas the situation is reversed for the MHD fast waves. For a thin current sheet (long-wavelength limit), the MHD slow wave becomes stagnant and very unstable, whereas the MHD fast wave propagates slowly and its stability depends on the strength of the background current. © 1997 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 56 (1995), S. 398-402 
    ISSN: 1432-0827
    Keywords: Calcium-binding ; Proteoglycan ; Bone matrix ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A calcium ion precipitable, trypsin-generated proteoglycan fragment has been isolated from the demineralized, EDTA-insoluble matrices of bone. The demineralized matrix was completely digested with trypsin, increasing concentrations of CaCl2 were added to the supernatant, and the resulting precipitates were analyzed. The amount of precipitate gradually increased with higher concentrations of calcium and was reversibly solubilized by EDTA. After molecular sieve and anion exchange chromatography, a proteoglycan-containing peak was obtained. Immunochemical analysis showed that this peak contained chondroitin 4-sulfate and possibly keratan sulfate. Amino acid analysis showed that this proteoglycan contained high amounts of aspartic acid/asparagine (Asx), serine (Ser), glutamic acid/glutamine (Glx), proline (Pro), and glycine (Gly); however, it contained little leucine (Leu) which suggests that it is not a member of the leucine-rich small proteoglycan family. In addition, significant amounts of phosphoserine (P-Ser) and hydroxyproline (Hyp) were identified in hydrolysates of this fraction. A single band (Mr 59 kDa) was obtained on SDS-PAGE that stained with Stains-all but not with Coomassie Brilliant Blue R-250. If bone powder was trypsinized prior to demineralization, this proteoglycan-containing fraction was not liberated. Collectively, these results indicate that a proteoglycan occurs in the demineralized matrix that is precipitated with CaCl2 and is closely associated with both mineral and collagen matrices. Such a molecule might facilitate the structural network for the induction of mineralization in bone.
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  • 3
    ISSN: 1432-0827
    Keywords: Key words: Bone collagen cross-links — HPLC — Polarizing microscopy — Paleoanthropology — Nuraghi population.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Bone collagen has a specific molecular ultrastructure which can be proved by birefringence. This protein, forming the main organic component of bone tissue, is known to survive millennia in paleontological bones and teeth. Birefringence of bone collagen obtained from the skeletons of the Nuraghi population living in Sardinia c-ca 1500 years B.C. was found previously by the use of polarizing microscopy [1]. In this paper, using high pressure liquid chromatography (HPLC) techniques, we show the existence of bone collagen cross-links preserved in Nuraghi skeletons after more than 3000 years.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-946X
    Keywords: Instruments ; Gamma-ray bursts ; X-ray emission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The High-Energy Transient Experiment (HETE) is designed for the multiwavelengths study of Gamma-Ray Bursts (GRBs) in UV, X-ray and gamma-ray range with three scientific instruments. The X-ray instrument, Wide-field X-ray Monitor (WXM), consists of four units of one-dimensional position sensitive gas proportional counters and two perpendicularly oriented one-dimensional coded apertures. The WXM has a wide FOV of 1.5 steradian together with the capability to locate GRBs with ∼ 10 arcmin accuracy, and covers photon energies of 2 to 25 keV with an energy resolution of typically ∼ 18 % at 6 keV, measuring wide band spectra together with the gamma-ray spectrometer (FREGATE). The coded X-ray image will be deconvolved on board and the GRB location will be provided to the UV camera within ∼ 1 sec . GRB locations will also be broadcast in “real time” to ground-based observers for follow-up observations.
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  • 5
    ISSN: 1572-9672
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 189 (1997), S. 145-153 
    ISSN: 1573-5036
    Keywords: coleoptile ; cultivar ; direct sowing ; flooded soil ; rice ; seedling establishment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seedling establishment of direct sown rice plants is less successful in flooded soil than in drained soil. This study was conducted to clarify the difference in morphogenesis of rice seeds sown in flooded and drained soils and to identify the morphological characteristics responsible for successful establishment of cultivars in flooded soil. Rice cultivars ASD1 and IR41996–50–2–1–3, superior in seedling establishment in flooded soil, and Mahsuri and IR72, non-superior (control), were sown at a depth of 25 mm in soil flooded with 25 mm of water or in drained soil. The coleoptile and 1st leaf emerged from the soil surface simultaneously in drained soil while in flooded soil the coleoptile emerged first. The coleoptile of superior cultivars, unlike the controls, elongated more in flooded soil than in drained soil. In flooded soil, the development of mesocotyl, 1st leaf, and roots were inhibited to a greater extent in the controls, than in the superior cultivars. In sealed flasks in which gas containing 0–21% O2 was exchanged daily, the superior cultivars developed longer coleoptiles than the controls at lower O2 concentrations. These findings suggest that the reason superior cultivars grow better in flooded soil than the controls is that the coleoptile elongates faster and longer in hypoxia and is able to reach the soil surface where O2 is available.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 173 (1995), S. 21-28 
    ISSN: 1573-5036
    Keywords: bronzing ; iron toxicity ; rice ; stress ethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The relationship among iron toxicity, bronzing symptom, and stress-induced ethylene production (SEP) was investigated in detached rice (Oryza sativa L.) leaves during the vegetative-ripening stage and in whole plants during the vegetative stage. When Fe2+ (200 mg L-1) was applied to the detached leaf through a transpiration stream, SEP was higher in the first leaf than in the second and third leaves from the top and maximal around the panicle primordia initiation stage. The genotype difference in SEP was more pronounced in the second and third leaves than in the first leaf. Bronzing intensity increased as SEP increased; iron concentration increase during treatment in the tissue did not correlate with bronzing intensity or with SEP among the 16 genotypes tested. When the roots of an intact plant were exposed to 300 mg L-1 of Fe2+ in culture solution little stress-induced ethylene was produced. By partially or totally derooting the plant, however, stress-induced ethylene was evoked, indicating that roots reduced the Fe2+ uptake so that little stress ethylene is produced in the intact plant. Leaf tissue tolerance for Fe2+ may contribute to genotype differences in iron toxicity tolerance of rice plants when roots are injured during transplanting or exposed to toxic substances in the soil.
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  • 8
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Proteoglycans are complex macromolecules containing one or more glycosaminoglycan chains and exhibiting a variety of biological functions in connective tissues. The aim of the present study was to immunolocalize the distribution of keratan sulphate and chondroitin sulphate epitopes during initial enamel formation in order to study temporo-spatial expression patterns of these macromolecules. Third molars of four-months-old pigs were used for immunolocalization of keratan sulphate and chondroitin sulphate epitopes in the developing enamel layer. Tooth organs were prepared for paraffin sections in order to perform indirect immunohistochemistry. The results demonstrated a mutually exclusive positioning between these two epitopes. Keratan sulphate epitopes were observed in pre-secretory pre-ameloblasts and adjacent stratum intermedium while chondroitin sulphate epitopes were demonstrated in secretory ameloblasts and adjacent stratum intermedium. Our findings suggest that proteoglycans containing glycosaminoglycan chains may play a regulatory role during enamel mineralization.
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  • 9
  • 10
    Publication Date: 1997-01-20
    Print ISSN: 0031-9007
    Electronic ISSN: 1079-7114
    Topics: Physics
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